This invention relates to electric arc welding and especially to an arc welding torch with a built-in optical system which permits real time observation of the weld puddle.
Good arc welds are achieved by controlling weld current, weld penetration, centering of weld puddle over part seam, weld bead lay rates, etc. When welding manually, the operator observes the welding process from an oblique angle and attempts to manipulate the weld torch and power supply adjustments to obtain good welds on the basis of intuition and prior experience. With machine welding, weld parameters are averaged based on past experience, and the machine programmed to weld with these inputs. Often this open loop machine welding does not produce good welds. For consistently good machine welding, some means for sensing weld puddle characteristics and using this information as feedback to control the welding process is needed.
Some experiments have been conducted at the Ohio State University Center for Welding Research in which the weld puddle has been viewed by an overhead optical system looking down over the welding electrode. In these experiments, the welding torch, open optical system, and video camera were carried on a large platform unsuitable for any practical welding application. The welding torch itself is conventional except that the lower part and electrode are bent through 90.degree. and provided with a window. See CWR Technical Report 529613-81-3, S. H. Rao, September 1981, pages 27-33.